Wideband integrated services local communication system

Abstract

The system comprises a plurality of units arranged along a unidirectional line whereupon information is transmitted relevant to circuit switched and packet switched communications and organized into hybrid frames comprising a region for each communication type. The units comprise devices handling the access to the line which cooperate with one another and with a frame signal generator, centralized or associated with each unit, to implement in distributed way an ordered protocol without collisions in both frame region, based on physical unit location.

We claim: 
     
       1. Wide-band intergrated services communication system, where there are transmitted both packet-switched and circuit-switched communications comprising: plurality of units;   plurality of stations coupled to said units;   transmission line coupled to said units through which information emitted by one of said stations is rendered available to others of said stations, whereby in presence of both packet-switched and circuit-switched communications, said information of all said stations is organized into hybrid frames subdivided into two regions allotted to circuit-switched communications, hereafter referred to as a circuit region, or to packet-switched and to signalling of circuit-switched communications, hereafter referred to as packet region;   whereby said units comprising:   means for controlling access to said transmission line for said information transmission and reception on basis of existing activity whereby said means controlling access to said transmission line are coupled to said transmission line as to detect at least activity of said units placed more upstream with reference to direction of transmission of said transmission line and cooperate with each of said units;   means for frame synchronization; whereby:   in each of said two frame regions, activity of said units with said information to be transmitted is subdivided into rounds, during which each of said units is ensured access to said transmission line for transmission of said information of each of said units, each of said rounds for information transmission concerning said circuit-switched communications coinciding with said circuit region of one of said frames, while said rounds for information transmission concerning said packet-switched communications can be completely contained within said packet region of one of said frames or said packet-switched communications can be contained over plurality consecutive of said frames;   in said circuit region and said packet region said units access said transmission line for transmission of information generated by said stations in order corresponding to position of said units along said transmission line, beginning from one of said units which is most upstream, referring to transmission direction on said transmission line;   in said circuit region, active period of one of said units has a duration varying from frame to frame according to instantaneous requirements of communications to which said information transmitted by said stations coupled to said units refers; and   said stations send said information according to predetermined order, which is maintained for said activity, said active period being separated by inactivity periods which depend on position of said units with respect to said transmission line, a guard signal effective during a predetermined guard time, and said inactivity periods are shorter than said predetermined guard time said guard time being exceeded in case of lack of activity of one of said unit.   
     
     
       2. A system as defined in claim 1 whereby in each of said units said means for controlling access to said transmission line comprise a pair of logic networks which recognize the access right of said units to which said units belong, during said circuit region or said packet region, respectively, by counting said inactivity periods and the number of times by which said guard-time is reached. 
     
     
       3. A system as defined in claim 1, whereby each of said unit comprises means to encode said information to be transmitted according to a self-synchronizing code and for transmitting bit patterns forming a violation of said code to separate said information relevant to different stations and to indicate end of activity and lack of activity of one of said stations. 
     
     
       4. A system as defined in claim 3 whereby each of said units performs a regeneration of signals coming from upstream prior to transmission of said information, said means to encode transmit further bit patterns to indicate the end of activity of a unit and to implement said inactivity periods and/or guard times. 
     
     
       5. A system as defined in claim 1 whereby said information relevant to circuit-switched communications generated by different stations of one of said units are organized during said circuit-switched activity, of one of said units during one of said frames so that there is an alternation of said information relevant to first type of communications, whereby source is characterized by emissions and pauses, and said information relevant to a second type of communications, whose source presents a continuous emission during the whole communications, and in that said means controlling access in each of said units further comprise a logic network counting number of communications of said first type originated by stations associated with said preceding units and with said unit itself and active during said frame, and enable transmission of said information relevant to further communications of same type, only if said number is lower than predetermined maximum. 
     
     
       6. A system as defined in claim 1 whereby said means for frame synchronization is unique for all of said units. 
     
     
       7. A system as defined in claim 1 whereby each of said units is associated with a generator of frame signals. 
     
     
       8. A system as defined in claim 7 whereby said frame signal generator is coupled between transmission branch and receiving branch of said transmission line and comprises a first means for generating Start-of-Frame flag, apt to send said flag on said transmission branch with constant periodicity; a second means for generating signals separating said two regions of frame and a third means for generating signals indicating the beginning of packet rounds, said second and third means for generating being enabled by frame and round recognizer, associated with said reception branch, when said recognizer recognizes the beginning of said frame and of said packet region, respectively, event to be signalled being recgnized by counting said units which had the access right in circuit and in said packet region of the frame, respectively. 
     
     
       9. A system as defined in claim 1 further comprises a pair of unidirectional lines on which the transmission takes place in opposite directions and along which said units are arranged, said units being connected to both lines by signal regenerators, and in that said frame signal generator comprises two identical elements each associated with one of said lines and inserted without regeneration between two ends of the respective line. 
     
     
       10. A system as defined in claim 9 whereby each of said units comprises separate devices for controlling the access to each of said lines. 
     
     
       11. A system as defined in claim 8 further comprising at least one main line along which a plurality of said units is arranged some of said units being connected to one of said units connected to one or more secondary lines associated with each of said respective frame signal generators and apt to convey said hybrid frames whose length is equal to that of frame on said main line, said units of said main line connected to said units associated to secondary lines inserting on said main line, in correspondence with their access turn, said circuit or said packet information relevant to said hybrid frames transmitted on said secondary lines.